Hi all.
This is the full story with... FIX! :-)
Let me try to make a good "googleable" summary (it took me so much time
to sort this out, I'd be happy if someone finds it useful).
The story begins like this: I was trying to limit the number of
simultaneous connections per virtualhost on Apache 2.0.58 running as a
reverse proxy.
1) Apache doesn't allow to limit simultaneous connections per
virtualhost (MaxClient only works at server level).
2) A few modules exist, but I never managed to have them working with
[reverse] proxy. => they only worked when Apache is working as a web
server.
What I realized was quite simple, but so sad: the modules were called
AFTER mod proxy. Which makes them useless!
Thanks to the only answer I had on the forum (thanks a lot to Joshua
Slive), I found solutions to change the order in which modules are
called.
I never managed to make mod_cband work (never managed to contact the
developer either), but by hacking mod_vhost_limit, that finally worked.
All modules register to Apache using the following function:
static void register_hooks(apr_pool_t *p)
{
ap_hook_handler(vhost_limit_handler, NULL, NULL,
APR_HOOK_REALLY_FIRST);//APR_HOOK_MIDDLE);
ap_hook_post_config(vhost_limit_init, NULL, NULL,
APR_HOOK_REALLY_FIRST);//APR_HOOK_MIDDLE);
}
Last parameter says "load this module somewhere". Changing
APR_HOOK_MIDDLE to APR_HOOK_FIRST would have been too easy: mod_proxy
allready says "I'm first" with this value!! Then I found the magic
"APR_HOOK_REALLY_FIRST" that finally made the module loaded first. I
guess next version of Apache will get the "APR_HOOK_REALLY_REALLY_FIRST"
value, and so on :-)
I can now limit the number of simultaneous connections per virtualhost,
before they are forwarded to the webserver by mod proxy.
I'm happy.
Olivier
PS: I will try to contact mod_vhost_limit creator to share the hacking.
Open source rules ;-)
Olivier CHIROUZE
I&0 Infrastructure
Volvo Information Technology
> -----Original Message-----
> From: Chirouze Olivier
> Sent: 09 February 2007 17:08
> To: 'users@xxxxxxxxxxxxxxxx'
> Subject: Trying to limit connections per virtual host with mod_cband
>
> Hi,
>
> I'm trying to use mod_cband... but can't manage to!
>
> I've tailed down my conf file to the most simple case with
> just one virtual host.
> What I'm trying to achieve is quite simple: I just want to
> limit the number of concurrent connections per virtual host
> (a "MaxClient" at the virtualhost level) and I think this is
> one of the many features of cband.
>
> How do I test this? Just call multiple times a page that
> takes very long to anwser: during all this time, for each
> click, a connection on this virtual host stays open on
> Apache. (thanks a lot to Georgi Chorbadzhiyski for pointing
> me to /status?notable that proves the connections are open on
> the right virtual host).
>
> The thing is, on cband-status, I see some rps used, but never
> a single connection! (thanks to cband status page:
> /cband-status). "Current connection" always stays at 0. And,
> in fact, the limit is never used. I set it to 2 and can have
> more than 10 concurrent connections. So, in a word, it
> doesn't work as expected.
>
> However, I see some "remote client", but always one. The
> virtual host is correct, but "Connections Limit/Current"
> always says "1/0". I don't understand how a line can be here
> with zero connection?
>
> I'm kind of lost after looking around for days and trying all
> I can think of (simplifying the config file, unactivating
> modules, changing order of LoadModule, using OpenSta, etc...)
>
> I'm using mod_rewrite and mod_proxy and I think that might be
> the pb. But there is an example with mod_rewrite on cband
> homepage so I suppose there is no incompatibility!
>
> Please... Help ;-)
>
> Olivier
>
> Olivier CHIROUZE
> I&0 Infrastructure
>
> The conf file:
> --------------------------------------------------------------
> ------------------------------------------
>
> ServerRoot /data/apache/httpd-test1
>
> # This only contains standard httpd.conf file with the
> following modules activated:
> #LoadModule access_module modules/mod_access.so
> #LoadModule log_config_module modules/mod_log_config.so
> #LoadModule logio_module modules/mod_logio.so
> #LoadModule env_module modules/mod_env.so
> #LoadModule setenvif_module modules/mod_setenvif.so
> #LoadModule ssl_module modules/mod_ssl.so
> #LoadModule mime_module modules/mod_mime.so
> #LoadModule status_module modules/mod_status.so
> #LoadModule negotiation_module modules/mod_negotiation.so
> #LoadModule dir_module modules/mod_dir.so
> #LoadModule alias_module modules/mod_alias.so
> Include
> /data/apache/httpd-test1/appli-apache/conf/httpd_solaris28.conf
>
> ServerName reverse-proxy-test2.iteu.volvo.net
>
> User apache
> Group apache
>
> DocumentRoot "/data/apache/httpd-test1/htdocs"
>
> ServerAdmin apache@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>
> LoadModule cband_module choucroutemodules/mod_cband.so
>
> LoadModule proxy_module modules/mod_proxy.so
>
> LoadModule proxy_http_module modules/mod_proxy_http.so
>
> CustomLog /logs/apache/httpd-test1/logs/rproxy_log "%{Host}i
> |%{RULE}e| %{%H/%T}t %h -> %{SERVER}e URL: %U"
>
> UseCanonicalName Off
>
> <VirtualHost reverse-proxy-test2.iteu.volvo.net:80>
> <Location /status>
> SetHandler server-status
> Order deny,allow
> Allow from all
> </Location>
> <Location /info>
> SetHandler server-info
> </Location>
> </VirtualHost>
>
> LoadModule rewrite_module modules/mod_rewrite.so
>
> RewriteEngine on
> RewriteLog /logs/apache/httpd-test1/logs/rewrite_log
> RewriteLogLevel 0
>
> LogLevel debug
>
> Listen reverse-proxy-test2.iteu.volvo.net:80
> NameVirtualHost reverse-proxy-test2.iteu.volvo.net:80
>
> <IfModule mod_cband.c>
> <Location /cband-status>
> SetHandler cband-status
> Order deny,allow
> Allow from all
> </Location>
> <Location /cband-status-me>
> SetHandler cband-status-me
> Order deny,allow
> Allow from all
> </Location>
> </IfModule>
>
> <IfModule mod_cband.c>
> CBandSpeed 0 0 10
> CBandScoreFlushPeriod 1
> CBandRandomPulse On
> </IfModule>
>
> <VirtualHost reverse-proxy-test2.iteu.volvo.net:80>
> ServerName youpi.volvo.net
>
> <IfModule mod_cband.c>
> CBandRemoteSpeed 0 3 1
> CBandSpeed 0 0 2
> CBandDefaultExceededCode 503
> CBandScoreboard /tmp/apache/scoreboard
> CBandPeriod 2s
> </IfModule>
>
> RewriteEngine on
> RewriteLog /logs/apache/httpd-test1/logs/rewrite_log
> RewriteLogLevel 3
> Include conf/deny_patterns.conf
>
> RewriteRule ^/(.*)$ http://10.213.131.69/waitZoub.php?wait=$1 [P]
>
> ProxyRequests off
>
> KeepAlive Off
>
> </VirtualHost>
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